The pathology lab at the hospital was locked down as specialist equipment was used to make safe the area.

Six fire engines were sent as a precaution to the hospital at 8pm.

A spokeswoman for Lancashire Teaching Hospitals NHS Foundation Trust said: “We can confirm that there was an accidental spillage in the pathology laboratory at Royal Preston Hospital this evening. As is standard protocol we evacuated a small number of staff from the laboratory, and contacted Lancashire Fire and Rescue Service which attended the hospital to help us resolve the matter. There is no risk to patients, visitors or staff and services are not affected. We would like to thank our colleagues at Lancashire Fire and Rescue for their prompt response and assistance.”

A spokeswoman for Lancashire Fire and Rescue Service said: “We were called just after 8pm on Friday evening to a leak in the pathology laboratory at Royal Preston Hospital. Six fire engines and two specialist appliances were used to identify the substance and make the scene safe for private contractors to finish the cleaning up process.”